1. Field of the Invention
The field of the invention is that of the fabrication of optical lenses, especially ophthalmic lenses intended to form spectacle lenses.
The invention more particularly concerns a flat molding method and a device for obtaining this kind of optical lens from a polymerizable material, these methods and devices involving the use of molding shells.
2. Description of the Related Art
It is known that molding shells are routinely employed in this field to form the two internal surfaces of a mold corresponding to the two faces of the finished lens that is obtained after polymerization of the material in the mold.
There are known from the document U.S. Pat. No. 4,474,355 a device and a method of molding an ophthalmic lens that employs two shells and a support for the two shells that allows them to be disposed flat and at a distance from each other to form a mold.
For positioning the shells, this support includes a series of shoulders for each shell, each shoulder being formed in an upright projecting from an annular base.
The document FR 2 449 519 also describes a device employing two molding shells. An annular seal is adapted to receive the two shells and to provide a seal between them.
Thus the annular seals form with the shells a sealed molding cavity, the elasticity of the seal enabling the latter to deform to accommodate shrinkage of the material upon polymerization.
Moreover, the document DE 2 455 888 describes a device including two sets of shells, each set including a plurality of interconnected shells disposed side by side, these two sets of shells being adapted to be superposed so that the shells cooperate two by two, each facing another to form a molding cavity.